Drums containing petroleum products, various chemicals, and other liquids and materials, some of which may be corrosive, or toxic and thus a health hazard, are usually provided with a bung hole and a vent hole in their top covers. These holes are usually plugged with a bung and a vent closure, both threadably received in the respective holes to prevent leakage of the contents from the drums. To prevent contamination of the contents of the drums, and/or, the removal of the contents therefrom, locking means have been used to lock the bung and vent closures against removal.